Kathy Mirakovits, FSEC 1

Impression Evidence Shoeprints

Kathy Mirakovits, FSEC 2

Footwear and Tire Treads

•  Impression-one object makes physical contact with another leaving some of its physical characteristics on the recipient

•  Soft or pliable materials leave three dimensional impressions—putty, mud, concrete, soft dirt

•  Hard surfaces have two dimensional impressions—dirt, dust, blood, ink

Kathy Mirakovits, FSEC 3

Types of Impression Evidence Fingerprints Tire tracks

Footprints Firing pin impressions

Kathy Mirakovits, FSEC 4

Footwear Impressions

•  Footwear impressions maybe left at crime scenes, and in entry and exit locations of scenes

•  Footwear evidence may be overlooked due to: •  May be nearly invisible •  On uneven ground •  Trampled by other footwear •  Footwear evidence is misunderstood or undervalued

by police, detectives, judges, and juries •  Footwear evidence can be fragile—must use

photography and make casts of impressions

Kathy Mirakovits, FSEC 5

Individual v. Class Evidence

•  New shoes without wear: generally class evidence •  With wear and tear: imperfections, alterations and

random markings cause shoes to individualize •  Abundance of unique details allows a competent

examiner to conclude the impression came from a particular shoe

•  No agreed upon standards for: -number of points of identification

-type or quality of the ID points •  From a good impression—size and type of shoe •  Manufacturing imperfections add discrimination

Kathy Mirakovits, FSEC 6

Athletic Shoe With Unique Patterns

• wear patterns highlighted

• imbedded materials highlighted

Kathy Mirakovits, FSEC 7

Footwear Impressions

•  Formed by a shoe deforming a surface •  May leave three dimensional impressions •  Trace evidence may be transferred from shoe to

surface (positive impression) •  Trace evidence may be transferred from surface

to shoe (negative impression) •  Static electricity build up can increase transfer of

material

Kathy Mirakovits, FSEC 8

Preservation of Footwear Impressions

•  Photograph footprints •  Photograph footprint with ruler or measuring tool

for court testimony •  In two dimensional footprint cases, photo will be

used for comparison •  Three dimensional footprints are casted: using

material that fills impression and then hardens to capture impression image

Kathy Mirakovits, FSEC 9

Casting Footwear

•  The primary material of choice to cast footprints is dental stone due to its hardness and ability to capture detail

•  Captures detail of footprint to a much greater extent than other materials, such as plaster of paris